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3 years ago

Mariana solved the equation below. Identify her ERROR and EXPLAIN what she did wrong. -3(2x-4)=-12 -6x-12=-12 -6x=0 x=0

Mathematics

1 answer:

nydimaria [60]3 years ago

8 0

Answer:

Her error was multiplying -3 and -4 which gives +12 but she wrote -12 instead

Step-by-step explanation:

Mariana workings:

-3(2x - 4) = -12

-6x - 12 = -12

Her error was multiplying -3 and -4 which gives +12 but she wrote -12 instead

-6x = 0

x=0

Correct workings:

-3(2x - 4) = -12

-6x + 12 = - 12

-6x = -12 - 12

-6x = -24

x = -24/-6

x = 4

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A space telescope on a mountaintop is housed inside of a cylindrical building with a hemispheric dome. If the circumference of t

Vlad1618 [11]

Answer:

$185553.7\text{ feet}^3$

Step-by-step explanation:

GIVEN: A space telescope on a mountaintop is housed inside of a cylindrical building with a hemispheric dome. If the circumference of the dome is $84\text{ feet}$ , and the total height of the building up to the top of the dome is $91\text{ feet}$ .

TO FIND: what is the approximate total volume of the building.

SOLUTION:

let the height of the mountaintop be $h\text{ feet}$

As the dome hemispherical.

circumference of a hemisphere $=\frac{1}{2}\times2\pi\times radius$

$=\pi\times radius$

$\frac{22}{7}\times radius=84$

$radius=26.75\text{ feet}$

total height of the building up to the top of the dome $=\text{radius of hemisphere}+\text{height of mountaintop}$

$=26.75+h=91$

$h=64.25\text{ feet}$

Volume of building $=\text{volume of cylindrical mountaintop}+\text{volume of dome}$

$=\pi(radius)^2h+\frac{2}{3}\pi(radius)^3$

as radius of mountain top is same as dome

putting values

$=3.14(26.75)^264.75+\frac{2}{3}3.14(26.75)^3$

$=145484.6+40069.1$

$185553.7\text{ feet}^3$

Hence the total volume of the building is $185553.7\text{ feet}^3$

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Or if you want to do it the long way you can calculate the actual discount (your savings from this purchase first then subtract it from the original price of $84. It`s just easier to figure out what is left (which is 70% of $84).

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